Functional polymers, porous silica particle surfaces

The present study is concerned with the modification of functional polymers onto porous silica particle surfaces. Our primary interest is to improve particle surface characteristics. Poly(acrylic acid) was chosen as the functional polymer to provide pH-intelligent, surface-responsive particles. The PAA chains under acid conditions are usually coiled, while under basic conditions the chains are extended due to electrostatic repulsion of the carboxylate ions. By controlling the pH, the surface characteristics can be tailored to respond to specific pH environments. Pore size distribution and specific surface area of modified silica are calculated from the amount of nitrogen adsorbed on the surface. The water penetration rate and porosity for different pH were measured for estimation of the surface properties ... 

This study is devoted to the investigation of porous methacrylate polymeric systems filled with chemically modified fumed silicas. IR and 13C NMR spectroscopies combined with AFM was applied to characterize changes in the material structure, and also the effect of surface functional groups of inorganic particles on the polymer-filler interaction. 

Lipases are manufactured by fermentation of selected microorganisms followed by a purification process. The enzymatic interesterification catalysts are prepared by the addition of a solvent such as acetone, ethanol, or methanol to a slurry of an inorganic particulate material in buffered lipase solution. The precipitated enzyme coats the inorganic material, and the lipase-coated particles are recovered by filtration and dried. Various support materials have been used to immobilize lipases. Generally, porous particulate materials with high surface areas are preferred. Typical examples of the support materials are ion-exchange resins, silicas, macroporous polymers, clays, etcetera. Effective support functionality requirements include (i) the lipase must adsorb irreversibly with a suitable structure for functionality, (ii) pore sizes must not restrict reaction rates, (iii) the lipase must not contaminate the finished product, (iv) the lipase must be thermally stable, and (v) the lipase must be economical. The dried particles are almost inactive as interesterification catalyst until hydrated with up to 10% water prior to use. 

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